Foldable leg construction



Nov. 3, 1964 C. l. M CALL FOLDABLE LEG CONSTRUCTION Filed July 5, 1963 J0 INVENTOR.

'lar'eflce 1. Me Call #GENT United States Patent 3,155,362 FOLDABLE LEG CONSTRUCTION v Clarence I; McCall, Waterbury, Qonm, assignor to Lewis Engineering Company, Naugatuck, (10:121., 21 corporation of Connecticut Filed July 5, 1963, Ser. No.293,62 0 8 Claims. (Cl. 248-359) venient tilted-back angle.

A feature of the invention resides in the provision of an improved support device in accordance with the foregoing, which involves relatively few parts of simple manufacture and assembly, whereby the fabrication cost is held to a minimum.

Another feature of the invention resides in the provision of an improved combination deten't device and end thrust means associated with the retractable leg, whereby a dual function is obtained, resulting in the elirri'ination of separate end thrust devices as such.

Other features and advantages will hereinafter appear.

In the drawings accompanying this specification, similar characters of reference are used to designate like components throughout the several views, in which:

FIG. 1 is a side elevational view on a reduced scale of an instrument casing having attached to the underside of its front portion a foldable supporting leg means as provided by the invention.

FIG. 2 is aside elevational view of the foldable leg construction, illustrated in extended position. This figure also shows a fragmentary portion of the instrument casing, on which the leg construction is carried.

FIG. 3 is a front elevational view of the extended leg construction shown in FIG. 2.

FIG. 4 is a bottom plan view of a housing component of the leg construction. 7

FIG. 5 is a side elevational view of the housing component of FIG. 4.

FIG. 6 is a bottom plan view of a cover plate associated with the housing component.

FIG. 7 is a rear elevational view of the extended leg per se.

FIG. 8 is a side view of a detent plunger of the device.

FIG. 9 is a front view of a bearing block provided for the 'detent plunger.

, PEG. 10 is a plan view of a detent and leg assemblage, illustrating a modification of the invention.

Referring now to the various figures, the extendable and retractable leg and mounting construction as illustrated comprises a housing 10' which may be advantageously fabricated as a metal stamping from sheet aluminum, for example. The housing 10 has coplanar :peripheral mounting portions 12 and 14, the latter being essentially -U-shaped as seen in FIG. 4. The mounting portions 12, 14 are adapted to .be secured to the underside of the front portion of an instrument casing, such as the casing 16 illustrated in FIGS. l-3. In FIG. 1

.the instrument casing 16 is shown as having a pair of low rubber feet or bumpers 18 adjoining the rear edge of the bottom or underside. It will be understood that the front portion of the bottom or underside may have either one or several of the extendable and retractable leg constructions' of the invention, as described herein.

The housing 10' has a downwardly offset central bearing p'ortionZii which may advantageously comprise a rectangular configuration as seen in FIG. 4. The offset bearing portion 20 is located inwardly of the coplanar mounting portions 12 and 14, and includes a flat bottom wall 22 together with downwardly extending side walls 24and 26 defining the periphery of the bottom wall 22; Cooperable with the housing 10 is a combined bearing and base plate 30 of rectangular configuration, said plate being disposed broadside to the housing and being engaged with the mouting portions 12, 14*thereof to form, withthe oifset portion 20, an enclosure for detent means described indetail below. Also, the plate 30 in conjunction with the bottom wall 22 of the offset portion provides an expansive bearing surface for a foldable sup port member or leg indicated generally by the numeral 32.

To'accommodate the support member 32 opposite portions of the side walls 26 of the housing 19 and also adjoining mounting portions of the housing have a pair of open-ended bearing slots 34, 36 so arranged that the base plate 39 close s oif end portions of the slots, as seen for example in FIG. 2.

The swingable support member 32 comprises a pair of legs 38, 4i) and a yoke 42 joining the legs, said yoke having cylindrical bearing surfaces 44, 46 arranged for engagement with the edges of the open-ended slots'34, 36 of the housing Ill. The cylindrical bearing surfaces 44, 46 also, in accordance with the invention, have line contact or engagement withthe base plate 30 as well as with the flat bottom wall'22 of the offset portion 20 of the housing 10. Such line engagement provides an extended or expansive bearing surface for the support member 32, in addition to the bearing surfaces constituted by the edges of the slots 34, 36. By such arrangement the support member may be swung between a retracted position folded back against the casing underside and an extended position extending downward from the underside, the later being indicated in FIGS. 1 and 2. In FIG. 1, the folded-back position is shown by broken lines.

For the purpose of yieldably holding the support member in either the retracted or else the extended position a novel detent device is provided, located in the housing 10 and specifically in the enclosure formed by the offset portion 20 and the base plate 30. The detent means comprises a headed plunger or pin 48 which is slidably carried in a bore '50 of a bearing block 52. A head 54- on the pin 48 is engageable with either of two flats56, 58 provided on the yoke 42 of the support member 32-. Behind the head 54 of the pin 48 is a helical compression spring 60 which is engaged with the bearing block 52 and yieldably holds the plunger pin engaged with one of the flats on the yoke '42.

As seen in FIGS. 1 and 2, the engagement between the plunger head 54 and the flat 56 yieldably holds the support member 32 in the downward extended position. From such position the member 32 may be swung backward and upward against the action of the plunger pin 48, elfecting a temporary retraction of such pin until it becomes engaged with the second fiat 58 of the support member 32. Such engagement will yieldably hold the supportmember in its retracted position as shown by the broken lines'in l.

The bearing block 52 snugly fits the interior of the offset portion 2lof the housing 10 and is held in agiven position against one of the walls 24 thereof under the action 'ofthe compression spring 60.

In the assembly of the device, the block 52 with the spring 66 and plunger pin 48 may be put in place after the placement of the support member 32 and prior to the application of the base plate 39. By virtue of the slots 34, 36 being open-ended, the placement of the yoke 42 of the support member 32 may be easily effected in the offset portion 20 of the housing. Thereafter, the placement of the detent mechanism is effected and lastly the base plate 30 is put in place. Temporary retention of such base plate may be easily and quickly had by the use of double coated adhesive tape strips placed along the mounting portions 12, 14. Such mounting portions, as well as the base plate, are preferably provided with matching sets of holes to accommodate fastening screws 64, by which the assemblage may be secured to the bottom wall of the casing 16.

The support member 32, in accordance with the invention, is formed of relatively large diameter round bar stock, such as aluminum rod, and may advantageously have a diameter of one-quarter inch. In forming the member 32 suitable bends are made to effect the yoke portion 42, and the flats 56, 58 may be machined in the yoke either prior or subsequent to the formation of the said bends. Additional bends are made in the legs 38, 40 of the support member 32, to form angle-shaped extremities 66 having juxtaposed ends 68. A rubber foot or shoe means comprising a single resilient tubular member 70 may be molded or otherwise provided around and enclosing both of the extremities or ends 68 of the support member, as shown in FIGS. 2, 3 and 7. The rubber foot 70 effectively covers the unfinished ends 68 of the legs 38, 40 and in addition to providing a finished appearance, is an effective anti-skid means while at the same time providing protection against scratches which might otherwise be made on the supporting table surface.

An important feature of the invention resides in the novel construction of the detent 54 and yoke portion 42 of the leg structure by which the detent has an end thrust function, preventing endwise movement of the leg yoke.

Referring to FIG. 7 it will be seen that the position of the head portion 54 of the plunger pin 48, by virtue of its location between the shoulders which are formed when the flats 56, 58 are milled or otherwise machined in the yoke 42, enables the plunger pin 48 and head 54 to limit endwise movement of the yoke portion 42. Thus, there is eliminated the necessity for separate end thrust collars or the like, and as a consequence there is a saving of parts. It is readily understandable from an inspection of FIG. 7 that the head portion 54 will be engageable with the shoulders at the ends of either of the flats 56, 58 (for either position of the leg structure 32) whereby the leg structure is held centralized with respect to the housing 10. Thus, in a simple manner an end thrust device is included in the plunger detent mechanism.

A modification of the invention is illustrated in FIG. 10, wherein two plunger pins or detent devices are provided in the housing 10, thereby effecting a doubly strong detent action for preventing inadvertent collapse of the supporting structure 32. As seen in this figure, a hearing block 74 is provided, having a pair of bores 76, 78 to accommodate plunger pins 80, 82 respectively. Springs 84, 86 are carried by the pins 80, 82, and said pins have heads 88, 9t) engageable with elongate fiat portions or surfaces 92, 94 on a yoke portion 96 of the leg structure 98, The bearing block '74 may be accommodated in the housing in place of the block 52, and the leg structure 98 may be substituted for the first described leg structure 32. The presence of the two springs provides twice the detent action or resistance to folding and opening of the leg structure, thereby insuring against accidental movement of the same. As with the embodiment of the invention illustrated in FIGS. 1-9, the detent plungers (or more properly the head portions 88, 9d of the plungers) are engageable with the shoulders at the ends of the flats 92, 94 so as to function as an end thrust means, eliminating the necessity for separate thrust collars or the like and maintaining the leg structure 98 centralized in the housing it without any tendency for binding at the rounded bends of the yoke portion.

It will now be understood that by the present invention I have provided a rugged and durable yet easily operated retractable and extendable support means by which a casing or similar structure may be advantageously supported in a tilted-back position as shown in PEG. 1. The present improved support means is characterized by relatively large, adequate bearing surfaces between the member 32 and the housing and base plate 10, 30 respectively. The support means has appreciable strength and is not likely to get out of order, in addition to which relatively few readily manufactured components are required, involving a quickly and easy assembly.

Variations and modifications may be made within the scope of the claims, and portions of the improvement may be used without others.

I claim:

1. A folding leg construction for intrument casings and the like comprising, in combination:

(a) a housing having coplanar peripheral mounting portions adapted to be secured to the underside of a casing,

(b) said housing having a downwardly offset bearing portion located inward of the coplanar mounting portions,

(0) said offset portion including a flat bottom wall and downwardly extending side walls at the periphery of the bottom wall,

(d) a combined bearing and base plate disposed broadside to the housing and engaged with the mounting portions thereof, said plate forming withsaid offset portion an enclosure, said plate closing off end portions of the bearing slots,

(e) opposite portions of the side walls and adjoining mounting portions of the housing having a pair of open-ended bearing slots,

(f) a swingable support member having a pair of legs and a yoke joining the same and having cylindrical bearing surfaces, said yoke being disposed in both the enclosure and the open-end slots of the housing side walls, the bearing surface of the yoke being engaged with the housing whereby the support may be swung between a retracted position folded against the casing underside and an extended position extending downward from the underside,

(g) shoe means on the free ends of the legs of the support, for engagement with a table surface,

(h) a flat on the said yoke,

(i) a reciprocable detent plunger in the housing, en-

gaged with said flat,

(j) a bored block in the housing, slidably carrying the detent plunger,

(k) a spring on said plunger, said spring being engaged with the bearing block and plunger to yieldably hold the latter engaged with the flat of the yoke,

(I) said flat enabling the plunger to yieldably hold the support in the said extended position.

2. A folding leg construction as in claim 1, wherein:

(a) the swingable support member Comprises a bent bar,

(b) the legs of the support member have angle-shaped free end portions the extremities of which are juxtaposed and separate,

(0) the shoe means comprises a single resilient tubular member extending around and enclosing both the said extremities.

3. A folding leg construction as in claim 1, wherein:

(a) the swingable support member comprises a round bar having bends to provide the yoke and legs,

(b) the surface of the bar-comprises the said cylindrical bearing surfaces.

4. A folding leg construction as in claim 3, wherein:

(a) the base plate and yoke have a line contact constituting a bearing for the support member.

5. A folding leg construction as in claim 4, wherein:

(a) the flat bottom wall of the housing and the yoke have a line contact constituting a bearing for the support member.

6. A folding leg construction as in claim 1, wherein:

(a) there are shoulders on the yoke of the support member, at opposite ends of the said flat of said yokes,

(b) the detent plunger is engageable with the shoulders at the ends of the flat, to limit endwise movement of the yoke.

7. A folding leg construction as in claim 1, wherein:

(a) there is a second reciprocable detent plunger in the housing, engaged with the said flat,

(b) the bored block in the housing slidably carries the second detent plunger,

(c) there is an additional spring disposed on the second detent plunger, said spring being engaged with the bearing block and plunger to yieldably hold the latter engaged with the flat of the yoke.

8. A folding leg construction as in claim 7, wherein:

(a) there are shoulders at opposite ends of the flat on the said yoke,

(b) the said detent plungers are engageable with the shoulders at the ends of the flat on the yoke, to limit the shoulders at the ends of the flat on the yoke, to limit endwise movement of the said yoke.

References Cited in the file of this patent UNITED STATES PATENTS Loock et al. Sept. 8, 1953 

1. A FOLDING LEG CONSTRUCTION FOR INTRUMENT CASINGS AND THE LIKE COMPRISING, IN COMBINATION: (A) A HOUSING HAVING COPLANAR PERIPHERAL MOUNTING PORTIONS ADAPTED TO BE SECURED TO THE UNDERSIDE OF A CASING, (B) SAID HOUSING HAVING A DOWNWARDLY OFFSET BEARING PORTION LOCATED INWARD OF THE COPLANAR MOUNTING PORTIONS, (C) SAID OFFSET PORTION INCLUDING A FLAT BOTTOM WALL AND DOWNWARDLY EXTENDING SIDE WALLS AT THE PERIPHERY OF THE BOTTOM WALL, (D) A COMBINED BEARING AND BASE PLATE DISPOSED BROADSIDE TO THE HOUSING AND ENGAGED WITH THE MOUNTING PORTIONS THEREOF, SAID PLATE FORMING WITH SAID OFFSET PORTION AN ENCLOSURE, SAID PLATE CLOSING OFF END PORTIONS OF BEARING SLOTS, (E) OPPOSITE PORTIONS OF THE SIDE WALLS AND ADJOINING MOUNTING PORTIONS OF THE HOUSING HAVING A PAIR OF OPEN-ENDED BEARING SLOTS, (F) A SWINGABLE SUPPORT MEMBER HAVING A PAIR OF LEGS AND A YOKE JOINING THE SAME AND HAVING CYLINDRICAL BEARING SURFACES, SAID YOKE BEING DISPOSED IN BOTH THE ENCLOSURE AND THE OPEN-END SLOTS OF THE HOUSING SIDE WALLS, THE BEARING SURFACE OF THE YOKE BEING ENGAGED WITH THE HOUSING WHEREBY THE SUPPORT MAY BE SWUNG BETWEEN A RETRACTED POSITION FOLDED AGAINST THE CASING UNDERSIDE AND AN EXTENDED POSITION EXTENDING DOWNWARD FROM THE UNDERSIDE, (G) SHOE MEANS ON THE FREE ENDS OF THE LEGS OF THE SUPPORT, FOR ENGAGEMENT WITH A TABLE SURFACE, (H) A FLAT ON THE SAID YOKE, (I) A RECIPROCABLE DETENT PLUNGER IN THE HOUSING, ENGAGED WITH SAID FLAT, (J) A BORED BLOCK IN THE HOUSING, SLIDABLY CARRYING THE DETENT PLUNGER, (K) A SPRING ON SAID PLUNGER, SAID SPRING BEING ENGAGED WITH THE BEARING BLOCK AND PLUNGER TO YIELDABLY HOLD THE LATTER ENGAGED WITH THE FLAT OF THE YOKE, (L) SAID FLAT ENABLING THE PLUNGER TO YIELDABLY HOLD THE SUPPORT IN THE SAID EXTENDED POSITION. 